Polyvinyl ethers are industrially important materials as they are used as materials for electronic parts, lubricants, adhesives and so on. Realization of the ability to provide a polyvinyl ether with a reactive silicon-containing functional group, such as silyl group or siloxy group, at the terminal thereof, can be expected to lead to the creation of a variety of novel functional materials, by combining another compound (molecule) with the polyvinyl ether via such functional group or by replacing the functional group with another functional group. However, no concrete means are available for obtaining such a polyvinyl ester. More specifically, although there have hitherto proposed polymerization reactions of various types of vinyl ethers using a Lewis acid, in the broad sense of the word including protonic acids, carbonyl ion salts, metal halides and the like, no examples are found expressly reporting on a polymer having a functional group such as silyl group or siloxy group at the terminal thereof.
As a relevant polymerization including polymerization of a vinyl ether, there can be cited a cationic polymerization in which chlorosilane and a metal halide (Hg2Cl2) are used (Kageura et al., J. Polym. Sci., 11, 1109 (1972)). In the process described in this paper, no reference is made to the terminal of the polymer. Furthermore, use of the chlorosilane encounters a handling problem because chlorosilane easily decomposes due to hydrolysis, thereby producing hydrochloric acid. More specifically, while a hydrosilane having functional groups such as one to three alkyl groups attached to the silicon atom has good handling property in a polymerization reaction, it exhibits a polymerization activity only when activated with a transition metal catalyst.
Examples of the polymerization reactions of vinyl ethers using a hydrosilane activated by a transition metal catalyst are very few and found only in a report in which a cobalt complex (dicobalt octacarbonyl) is used (Crivello et al., J. Polym. Sci. A., 30, 31-39 (1992)), and in a patent application relating to an invention of a polymerization catalyst primarily composed of platinum for vinyl ethers (Japanese Patent Application Publication No. 17244/1994).
The paper of Crivello et al. relates to a polymerization process including an isomeric reaction of an allyl ether to a vinyl ether. With regard to the polymerization of the vinyl ether, while the molecular weight and molecular weight distribution of the polymer produced are set out, only one working example is given and no elucidation is found regarding the molecular structure of the polymer, including its terminal structure. In the above-mentioned patent application, nothing whatsoever is said regarding either the terminal structure of the polymer or the molecular weight and the molecular weight distribution of the polyvinyl ether.
The object of the present invention is to provide a polyvinyl ether having a silicon-containing functional group or atomic group, such as silyl group or siloxy group, at the terminal thereof and also a method for producing such polyvinyl ether as a novel polyvinyl ether.